/* FileSaver.js
* A saveAs() FileSaver implementation.
* 2013-01-23
*
* By Eli Grey, http://eligrey.com
* License: X11/MIT
*   See LICENSE.md
*/

/*global self */
/*jslint bitwise: true, regexp: true, confusion: true, es5: true, vars: true, white: true,
plusplus: true */

/*! @source http://purl.eligrey.com/github/fileSaver.js/blob/master/fileSaver.js */

var saveAs = saveAs
|| (navigator.msSaveOrOpenBlob && navigator.msSaveOrOpenBlob.bind(navigator))
|| (function(view) {
	"use strict";
	var	doc = view.document
	// only get URL when necessary in case BlobBuilder.js hasn't overridden it yet
	, get_URL = function() {
		return view.URL || view.webkitURL || view;
	}
	, URL = view.URL || view.webkitURL || view
	, save_link = doc.createElementNS("http://www.w3.org/1999/xhtml", "a")
	, can_use_save_link =  !view.externalHost && "download" in save_link
	, click = function(node) {
		var event = doc.createEvent("MouseEvents");
		event.initMouseEvent(
			"click", true, false, view, 0, 0, 0, 0, 0
			, false, false, false, false, 0, null
		);
		node.dispatchEvent(event);
	}
	, webkit_req_fs = view.webkitRequestFileSystem
	, req_fs = view.requestFileSystem || webkit_req_fs || view.mozRequestFileSystem
	, throw_outside = function (ex) {
		(view.setImmediate || view.setTimeout)(function() {
			throw ex;
		}, 0);
	}
	, force_saveable_type = "application/octet-stream"
	, fs_min_size = 0
	, deletion_queue = []
	, process_deletion_queue = function() {
		var i = deletion_queue.length;
		while (i--) {
			var file = deletion_queue[i];
			if (typeof file === "string") { // file is an object URL
				URL.revokeObjectURL(file);
			} else { // file is a File
				file.remove();
			}
		}
		deletion_queue.length = 0; // clear queue
	}
	, dispatch = function(filesaver, event_types, event) {
		event_types = [].concat(event_types);
		var i = event_types.length;
		while (i--) {
			var listener = filesaver["on" + event_types[i]];
			if (typeof listener === "function") {
				try {
					listener.call(filesaver, event || filesaver);
				} catch (ex) {
					throw_outside(ex);
				}
			}
		}
	}
	, FileSaver = function(blob, name) {
		// First try a.download, then web filesystem, then object URLs
		var
		filesaver = this
		, type = blob.type
		, blob_changed = false
		, object_url
		, target_view
		, get_object_url = function() {
			var object_url = get_URL().createObjectURL(blob);
			deletion_queue.push(object_url);
			return object_url;
		}
		, dispatch_all = function() {
			dispatch(filesaver, "writestart progress write writeend".split(" "));
		}
		// on any filesys errors revert to saving with object URLs
		, fs_error = function() {
			// don't create more object URLs than needed
			if (blob_changed || !object_url) {
				object_url = get_object_url(blob);
			}
			if (target_view) {
				target_view.location.href = object_url;
			} else {
				window.open(object_url, "_blank");
			}
			filesaver.readyState = filesaver.DONE;
			dispatch_all();
		}
		, abortable = function(func) {
			return function() {
				if (filesaver.readyState !== filesaver.DONE) {
					return func.apply(this, arguments);
				}
			};
		}
		, create_if_not_found = {create: true, exclusive: false}
		, slice
		;
		filesaver.readyState = filesaver.INIT;
		if (!name) {
			name = "download";
		}
		if (can_use_save_link) {
			object_url = get_object_url(blob);
			save_link.href = object_url;
			save_link.download = name;
			click(save_link);
			filesaver.readyState = filesaver.DONE;
			dispatch_all();
			return;
		}
		// Object and web filesystem URLs have a problem saving in Google Chrome when
		// viewed in a tab, so I force save with application/octet-stream
		// http://code.google.com/p/chromium/issues/detail?id=91158
		if (view.chrome && type && type !== force_saveable_type) {
			slice = blob.slice || blob.webkitSlice;
			blob = slice.call(blob, 0, blob.size, force_saveable_type);
			blob_changed = true;
		}
		// Since I can't be sure that the guessed media type will trigger a download
		// in WebKit, I append .download to the filename.
		// https://bugs.webkit.org/show_bug.cgi?id=65440
		if (webkit_req_fs && name !== "download") {
			name += ".download";
		}
		if (type === force_saveable_type || webkit_req_fs) {
			target_view = view;
		}
		if (!req_fs) {
			fs_error();
			return;
		}
		fs_min_size += blob.size;
		req_fs(view.TEMPORARY, fs_min_size, abortable(function(fs) {
			fs.root.getDirectory("saved", create_if_not_found, abortable(function(dir) {
				var save = function() {
					dir.getFile(name, create_if_not_found, abortable(function(file) {
						file.createWriter(abortable(function(writer) {
							writer.onwriteend = function(event) {
								target_view.location.href = file.toURL();
								deletion_queue.push(file);
								filesaver.readyState = filesaver.DONE;
								dispatch(filesaver, "writeend", event);
							};
							writer.onerror = function() {
								var error = writer.error;
								if (error.code !== error.ABORT_ERR) {
									fs_error();
								}
							};
							"writestart progress write abort".split(" ").forEach(function(event) {
								writer["on" + event] = filesaver["on" + event];
							});
							writer.write(blob);
							filesaver.abort = function() {
								writer.abort();
								filesaver.readyState = filesaver.DONE;
							};
							filesaver.readyState = filesaver.WRITING;
						}), fs_error);
					}), fs_error);
				};
				dir.getFile(name, {create: false}, abortable(function(file) {
					// delete file if it already exists
					file.remove();
					save();
				}), abortable(function(ex) {
					if (ex.code === ex.NOT_FOUND_ERR) {
						save();
					} else {
						fs_error();
					}
				}));
			}), fs_error);
		}), fs_error);
	}
	, FS_proto = FileSaver.prototype
	, saveAs = function(blob, name) {
		return new FileSaver(blob, name);
	}
	;
	FS_proto.abort = function() {
		var filesaver = this;
		filesaver.readyState = filesaver.DONE;
		dispatch(filesaver, "abort");
	};
	FS_proto.readyState = FS_proto.INIT = 0;
	FS_proto.WRITING = 1;
	FS_proto.DONE = 2;

	FS_proto.error =
	FS_proto.onwritestart =
	FS_proto.onprogress =
	FS_proto.onwrite =
	FS_proto.onabort =
	FS_proto.onerror =
	FS_proto.onwriteend =
	null;

	view.addEventListener("unload", process_deletion_queue, false);
	return saveAs;
}(self));

if (typeof module !== 'undefined') module.exports = saveAs;
